CellsCells All cells have All cells have twotwo

characteristics in characteristics in commoncommon Surrounded by a cell Surrounded by a cell

membranemembrane At some point contain At some point contain

DNADNA Two TypesTwo Types

Prokaryotic and Prokaryotic and EukaryoticEukaryotic

ProkaryotesProkaryotes

Generally smaller and Generally smaller and simplersimpler

Genetic material is Genetic material is not contained in a not contained in a nucleusnucleus

Grow, reproduce, Grow, reproduce, respond to the respond to the environmentenvironment

ExampleExample: Bacteria: Bacteria

EukaryotesEukaryotes

Generally larger and more Generally larger and more complexcomplex

Contain dozens of structures Contain dozens of structures and internal membranesand internal membranes

Highly specialized cellsHighly specialized cells Genetic material is contained Genetic material is contained

in a nucleusin a nucleus May be single celled May be single celled

organisms, or part of a large organisms, or part of a large multi-cellular organismmulti-cellular organism

Diversity of Cellular LifeDiversity of Cellular Life

Unicellular OrganismsUnicellular Organisms Made of a single cellMade of a single cell Majority of life on Majority of life on

EarthEarth

Multi-cellular Multi-cellular OrganismsOrganisms Made of many cellsMade of many cells Depend on Depend on

cooperation and cooperation and communication among communication among specialized cellsspecialized cells

Cell specializationCell specialization: cells : cells develop in different ways to develop in different ways to perform different tasksperform different tasks Animal cellsAnimal cells: red blood cells : red blood cells

(transport oxygen), (transport oxygen), pancreas (protein pancreas (protein production), muscle cells production), muscle cells (movement)(movement)

Plant cellsPlant cells: guard cells : guard cells (regulate exchange in (regulate exchange in leaves)leaves)

Levels of OrganizationLevels of Organization Individual CellsIndividual Cells

TissuesTissues Cells grouped togetherCells grouped together A group of similar cells that perform a particular A group of similar cells that perform a particular

functionfunction

OrgansOrgans Tissues work togetherTissues work together

Organ SystemsOrgan Systems Group of organs that work together to perform a Group of organs that work together to perform a

specific functionspecific function

Osmosis and DiffusionOsmosis and Diffusion

Chapter 7.3Chapter 7.3

Cell BoundariesCell Boundaries

Cell MembraneCell Membrane Thin flexible barrier that surrounds a cellThin flexible barrier that surrounds a cell Regulates what enters and leaves the cell, Regulates what enters and leaves the cell,

provides protection and supportprovides protection and support Cell WallCell Wall

Strong supporting layer around the cell Strong supporting layer around the cell membranemembrane

Gives protection and support to a plant cellGives protection and support to a plant cell

Cell Membrane StructureCell Membrane Structure

Made of two layers Made of two layers (lipid bilayer)(lipid bilayer) Gives cell membranes Gives cell membranes

a flexible structure that a flexible structure that forms a strong barrierforms a strong barrier

Contains protein and Contains protein and carbohydrate carbohydrate moleculesmolecules Helps materials cross Helps materials cross

the membranethe membrane

Cell Wall Cell Wall StructureStructure

Found outside Found outside the cell the cell membrane membrane (plants)(plants) Main function to Main function to

provide support provide support and protectionand protection

Allows water, Allows water, oxygen, carbon oxygen, carbon dioxide to pass dioxide to pass throughthrough

Made from Made from carbohydrates carbohydrates and proteinand protein

DiffusionDiffusion Movement of dissolved Movement of dissolved

molecules from one side molecules from one side of cell membrane to of cell membrane to anotheranother

Particles move from an Particles move from an area where they are more area where they are more concentrated to an area concentrated to an area where they are less where they are less concentratedconcentrated

Substances diffuse across Substances diffuse across a membrane without the a membrane without the cell using any energycell using any energy

OsmosisOsmosis Diffusion of waterDiffusion of water across a selectively across a selectively permeable permeable membranemembrane

Most membranes Most membranes selectively selectively permeablepermeable

• some substances some substances can pass through can pass through and others cannotand others cannot

• Water passes easily Water passes easily across most across most membranesmembranes

OsmosisOsmosis How Osmosis works…How Osmosis works…

Water will move across Water will move across the membrane until the membrane until equilibriumequilibrium is reached is reached

• Moves from high to low Moves from high to low concentrationconcentration

Osmotic pressureOsmotic pressure: : pressure on the pressure on the hypertonic side of a hypertonic side of a selectively permeable selectively permeable membranemembrane

SolutionsSolutions HypertonicHypertonic: side of the : side of the membrane with more membrane with more molecules; “above molecules; “above strength”strength”

HypotonicHypotonic: the side of the : the side of the membrane with less membrane with less molecules; “below molecules; “below strength”strength”

IsotonicIsotonic: concentrations : concentrations the same on both sides of the same on both sides of the membrane; “same the membrane; “same strength”strength”

Facilitated DiffusionFacilitated Diffusion

Cell membrane has Cell membrane has certain channels certain channels (proteins) that make it (proteins) that make it easy for certain easy for certain molecules to cross molecules to cross the membranethe membrane Will only occur if there Will only occur if there

is a higher is a higher concentration on one concentration on one side of the membraneside of the membrane

Active TransportActive Transport

Small molecules and ions are carried across Small molecules and ions are carried across membranes by proteinsmembranes by proteins Requires energy, cells use majority of their energy for Requires energy, cells use majority of their energy for

transporttransport

EndocytosisEndocytosis Process of taking material into the cell by folding of Process of taking material into the cell by folding of

cell membranecell membrane

ExocytosisExocytosis Membrane of vacuole fuses with cell membrane Membrane of vacuole fuses with cell membrane

forcing contents out of cellforcing contents out of cell